JP3390711B2 - Electrophotographic toner binder - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a toner binder for electrophotography.

[0002]

2. Description of the Related Art A method of using a contact heating type fixing device (heat roll) in order to fix the toner transferred onto a paper or the like in an electrophotographic process using powdery dry toner,
A method in which a film or a belt is interposed between the heating element and the paper (for example, JP-A-4-70688 and JP-A-4-70688).
No. 12558) is widely adopted. In this method, it is desirable that the minimum fixing temperature (hereinafter abbreviated as MFT) is low (low temperature fixing property), and the temperature at which hot offset occurs on the heat roll surface, film or belt (hereinafter abbreviated as HOT) is high. Is preferable (hot offset resistance). Further, in order to obtain a clear image, a toner having a high triboelectric charge amount is preferable (charging characteristics).

Conventionally, polystyrene resins, styrene-acrylic copolymers, polyester resins, epoxy resins and the like have been generally used as the binder component of this dry toner. Among them, polystyrene is preferable from the viewpoints of performance such as pulverizability and chargeability, and cost. Resins and styrene-acrylic resins are widely used. In order to satisfy the low-temperature fixability and the hot offset resistance, many methods for improving the resin by broadening the molecular weight distribution of the resin have been proposed. As a method for broadening the molecular weight distribution, a vinyl-based resin is used with a vinyl-based cross-linking agent (JP-A-61-215558).
JP-A-63-44665, JP-A-63-
No. 223,014, Japanese Patent Laid-Open No. 4-202307)
And in the molecular weight distribution, 2
Toner binder with two peaks (Japanese Patent Publication No. 63-3
2180, JP-B-63-32382) or a toner binder obtained by crosslinking a carboxyl group-containing vinyl resin with a glycidyl compound (JP-A-6-11890).
JP-A-6-222612) and the like are proposed.

[0004]

[Problems to be Solved by the Invention] However, as described above,
In a conventional toner binder having a crosslinked structure, a phenomenon in which the crosslinked portion is severely molecule-cut by kneading at the time of forming a toner, and the melt elasticity of the toner is lowered, is observed. Therefore, in order to maintain hot offset resistance, it is necessary to use a large amount of cross-linking components and high molecular weight components, and with that, the melt viscosity of the resin is significantly higher than that of a resin without a cross-linking structure. Was becoming. From this, the cross-linked toner binder tends to deteriorate the low temperature fixing property of the toner as compared with the non-cross-linked toner binder. Further, in the conventional method of crosslinking by utilizing the reaction of functional groups in the polymer, in order to improve the hot offset resistance, if the amount of functional groups is increased and the degree of crosslinking of the binder is increased, the amount of polar groups increases. However, the charging property of the toner binder becomes insufficient. As described above, in the conventional technology, there is a demand for high image quality of recent copying machines, facsimiles, and printers, and a trend of demanding higher hot offset resistance and lower temperature fixing property in accordance with speeding up and downsizing of hardware. It's hard to say that we are fully prepared.

[0005]

Means for Solving the Problems As a result of intensive studies to solve these problems, the present inventors have increased the weight average molecular weight of the epoxy group-containing resin and
By reducing the content of epoxy groups to a very low level, we have developed a technology that makes it difficult for the cross-linked portion to be cut during kneading in the toner formation process and for the melt elasticity of the toner to be less likely to decrease. That is, the present invention provides an electrophotographic toner binder comprising a styrene-acrylic resin (A) having a carboxyl group and a styrene resin (B) having a functional group (b) that reacts with a carboxyl group, wherein (A) is Weight average molecular weight of 200,000 ~
High molecular weight polymer (C) of 2 million and weight average molecular weight of 3
A low molecular weight polymer (D) having a weight average molecular weight of 000 to 50,000, a weight average molecular weight of (B) of less than 1 and a weight average molecular weight of 30,000 to 1,000,000. is there.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below. As a method for obtaining the styrene-acrylic resin (A) having a carboxyl group of the present invention, a method of copolymerizing a vinyl monomer having a carboxyl group with a styrene monomer and an acrylic monomer is preferable. Examples of the vinyl monomer having a carboxyl group include (meth) acrylic acid, maleic acid, fumaric acid, cinnamic acid, and monoesters of unsaturated dibasic acids such as monoalkyl maleates (having 1 to 6 carbon atoms). Among these, (meth) acrylic acid and monoalkyl maleate (having 1 to 6 carbon atoms) are preferable.

The styrene-based monomer used in the styrene-acrylic resin (A) having a carboxyl group is
Examples thereof include styrene, α-methylstyrene, p-methoxystyrene, p-hydroxystyrene and p-acetoxystyrene. Examples of the acrylic monomer include butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate and the like, in which the alkyl group has 1 to 1 carbon atoms.
8 alkyl (meth) acrylate and the like.
In order to increase the elasticity of the binder, a divinyl compound such as divinylbenzene, ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, divinyltoluene (A) is used. It is preferably used in an amount of 0.1 mol% or less with respect to all the monomers constituting the. More preferably, 0.00005-0.001mo
1%. Further, vinyl monomers other than these styrene-based monomers and acrylic-based monomers may be copolymerized. Other vinyl monomers include
Examples thereof include vinyl esters such as vinyl acetate; vinyl ethers such as vinyl ethyl ether; aliphatic hydrocarbon vinyls such as α-olefin, isoprene and butadiene; and (meth) acrylonitrile.

The styrene-acrylic resin (A) comprises a high molecular weight substance (C) and a low molecular weight substance (D), and the weight average molecular weight of (C) is 200,000 to 2,000,000, preferably 30.
It is 10,000 to 1.8 million, and more preferably 400,000 to 1.5 million. If the weight average molecular weight is less than 200,000, the HOT of the toner will be lowered. If the weight average molecular weight exceeds 2,000,000, the MFT of the toner becomes high. The glass transition point of (C) is usually 40 ° C to 80 ° C. The acid value of (C) is less than 1, preferably 0.01 to 0.999, and more preferably 0.1 to 0.99.

As the polymerization method for producing (C), any method such as solution polymerization, bulk polymerization and suspension polymerization can be selected. The polymerization initiator is not particularly limited, and examples thereof include azo-based initiators such as azobisisobutyronitrile and azobisisovaleronitrile; benzoyl peroxide, di-t-butyl peroxide, lauroyl peroxide, dicumyl. Peroxide-based initiators such as peroxides; 2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane, 1,1-bis (t-butylperoxy) 3,3,5- Polyfunctional polymerization initiators having two or more peroxide groups in one molecule such as trimethylcyclohexane and di-t-butylperoxyhexahydroterephthalate; 1 such as diallylperoxydicarbonate and t-butylperoxyallylcarbonate Polyfunctional having one or more peroxide groups and one or more polymerizable unsaturated groups in the molecule Such as polymerization initiators, and the like. Of these, polyfunctional polymerization initiators are preferable.

The solvent for obtaining (C) by solution polymerization is not particularly limited, but may be toluene, xylene,
Aromatic solvents such as ethylbenzene, ester solvents such as ethyl acetate and butyl acetate, dimethylformamide,
Examples thereof include dimethyl sulfoxide and methyl ethyl ketone. Preferred are dimethylformamide, xylene, and toluene.

When (C) is obtained by suspension polymerization,
Polymerization can be carried out in water using an inorganic salt dispersant such as calcium carbonate or calcium phosphate, or an organic dispersant such as polyvinyl alcohol or methylated cellulose. The polymerization temperature is usually 50 to 160 ° C., preferably 60 to 140.
℃. The atmosphere during the polymerization is preferably carried out in the presence of an inert gas such as nitrogen.

The weight average molecular weight of the low molecular weight substance (D) is 30.
00-50000, preferably 3500-400
00, and more preferably 4000 to 30,000. If the weight average molecular weight is less than 3,000, the heat-resistant storage stability of the resulting toner becomes poor. If the weight average molecular weight exceeds 50,000, the MFT of the toner becomes high. The glass transition point of (D) is usually 40 ° C to 80 ° C. The acid value of (D) is usually smaller than 10, preferably 5 or less, and more preferably 1 or less. When it exceeds 10, the charging property of the toner deteriorates.

As the polymerization method for producing (D), any method such as solution polymerization, bulk polymerization and suspension polymerization can be selected. Of these, solution polymerization is preferred.
When the (D) is polymerized by solution polymerization, it can be polymerized by the solution polymerization method described above. The polymerization initiator for polymerizing (D) is not particularly limited, and examples thereof include the polymerization initiators described above. Preferred among these are monofunctional initiators.

The weight ratio of the high molecular weight substance (C) (A) to the low molecular weight substance (D) is usually 70/30 to 5/95.
It is preferably 60/40 to 10/90. More preferably, it is 50/50 to 20/80. The glass transition point (Tg) of (A) is usually 40 to 80 ° C., preferably 50 to 70 ° C. from the viewpoint of heat resistant storage stability when used as a toner and MFT when used as a toner. The acid value of (A) is
Less than 1, preferably 0.001-0.9,
More preferably, it is 0.01 to 0.8.

Examples of the functional group (b) which reacts with a carboxyl group include an epoxy group, an oxazoline group, an isocyanate group and an amino group. Among these, those having an epoxy group are preferable. Styrene resin of the present invention,
Alternatively, the method of introducing the reactive functional group (b) into the styrene-acrylic resin (B) is the vinyl monomer having the reactive functional group (b) as in the case of introducing the carboxyl group into the above-mentioned (A). And a styrene-based monomer or a styrene-based monomer and an acrylic-based monomer are copolymerized. Examples of the vinyl monomer having an epoxy group include glycidyl (meth) acrylate, β-methylglycidyl (meth) acrylate, and allylglycidyl ether. Of these, glycidyl (meth) acrylate is preferred. Examples of the vinyl monomer having an isocyanate group include m-isopropenyl-α, α-dimethylbenzyl isocyanate, methacryloyl isocyanate, 2-isocyanate ethyl methacrylate and the like. Among these, preferred is m-isopropenyl-α, α-dimethylbenzyl isocyanate. As vinyl monomers having an oxazoline group, 2-vinyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2
-Vinyl-5-methyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline and the like can be mentioned. Of these, 2-isopropenyl-2-oxazoline is preferable. Examples of the vinyl monomer having an amino group include aminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, 4-vinylpyridine, 2-vinylpyridine and the like. Among these, a tertiary amino group-containing (meth) acrylate is preferable. Examples of the monomer to be copolymerized with the monomer having (b) include the styrene-based monomer, the acrylic-based monomer, and other vinyl monomers described above. Among these, preferred are alkyl (meth) having an alkyl group having 1 to 18 carbon atoms, such as styrene, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate and stearyl (meth) acrylate. ) Acrylate.

As the polymerization method for producing (B), any method such as solution polymerization, bulk polymerization and suspension polymerization can be selected. Of these, bulk polymerization is preferred.
When the (B) is polymerized by bulk polymerization, it can be polymerized by the bulk polymerization method described above. The polymerization initiator for polymerizing (B) is not particularly limited, and examples thereof include the above-mentioned polymerization initiators.

The weight average molecular weight (BMW) of (B) used in the present invention is usually from 30,000 to 1,000,000, preferably 5
It is 10,000 to 700,000, and more preferably 100,000 to 600,000. The glass transition point of (B) is usually 30 ° C to 150 ° C, preferably 35 ° C to 90 ° C, more preferably 40 ° C to 80 ° C. The content of (b) in (B) is
It is 0.000001 to 1 mol, preferably 0.00001 to 0.1 mol, and more preferably 0.0001 to 0.01 mol in 100 g of the total amount of (B).

The method for producing the resin for toner of the present invention is (A)
It is obtained by mixing and (B) and heating. When the reaction is carried out without using a kneader, the hot offset property of the obtained toner binder is improved, which is more preferable. The kneaders mean a device having a charging part and a discharging part and continuously mixing and kneading resins, and specific examples thereof include a continuous kneader, a kneader ruder, a statics mixer and the like. Also,
When (A) and (B) are blended in powder form, it is possible to heat and react when preparing a toner. The weight ratio of (A) and (B) is usually 0.1 part to 30 parts for (B) per 100 parts of (A).
It is a department. Preferably (B) is 1 part to 25 parts, more preferably 10 parts to 23 parts. The functional group of (b) is 0.000 per 1 mol of the carboxyl group of (A).
It is 1 to 1 mol, preferably 0.001 to 1.0 mol, and more preferably 0.01 to 1.0 mol.

An example of a method for producing an electrophotographic toner which is an application of the toner binder of the present invention will be described. The toner binder is usually 45 to 95% by weight based on the weight of the toner, and a known coloring agent (carbon black, iron black, (Benzidine yellow, quinacdrine, rhodamine B, phthalocyanine, etc.)
Is usually used in an amount of 5 to 10% by weight, and magnetic powder (a compound such as iron, cobalt, nickel, hematite, and ferrite) is usually used in an amount of 0 to 50% by weight, and various additives [charge adjusting agent (metal complex, nigrosine Etc.), lubricants such as polytetrafluoroethylene, low molecular weight polyolefins, fatty acids, or metal salts or amides thereof, etc.] can be added. The amount of these additives is usually 0 to 10% by weight based on the weight of the toner. The toner for electrophotography is dry-blended with the above components, melt-kneaded, coarsely pulverized, and finally finely pulverized by using a jet pulverizer to obtain fine particles having a particle size of 5 to 20 μm. The electrophotographic toner, if necessary, iron powder, glass beads,
It is used as a developer for an electric latent image by mixing with carrier particles such as nickel powder and ferrite. In addition, hydrophobic colloidal silica fine powder may be used to improve the fluidity of the powder. The electrophotographic toner is a support (paper,
It is used after being fixed on a polyester film). The fixing method is as described above.

[0020]

The present invention will be further described with reference to the following examples, but the present invention is not limited thereto. Hereinafter, parts are parts by weight. The methods for measuring the properties of the resins obtained in the synthesis examples, examples and comparative examples are shown below.

[0021] Molecular weight measurement Device: Tosoh Corporation HLC-802A Conditions: Column Tosoh Corporation TSK gel GMHXL 2 pcs Measurement temperature: 40 ℃ Sample solution: 0.25 wt% tetrahydrofuran solution Injection volume: 100 μl Detector: Refractive index detector The molecular weight calibration curve was created using standard polystyrene.

Glass transition point (Tg) measuring device: DSC20, SS manufactured by Seiko Instruments Inc.
C / 580 condition: ASTM (D3418-2) method

Preparation of Resin (C) Production Example 1 764.6 parts of styrene, 234.4 parts of n-butyl acrylate, and monobutyl maleate of 0.14 in an autoclave reaction vessel equipped with a thermometer, a stirrer, and a nitrogen introducing tube. 8 parts, a mixed monomer of 0.2 parts of divinylbenzene and an initiator,
0.5 parts of 2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane was added, and in a nitrogen stream,
After polymerizing at 90 ° C. for 5 hours, 245 parts of xylene was added, and the mixture was polymerized at 90 ° C. for 1 hour and then at 110 ° C. for 1 hour. Furthermore, 0.1 part of 2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane and xylene 1
Add 22 parts and polymerize at 110 ° C for 4 hours, then 150 ° C
Then, 1 part of di-t-butyl peroxide and 25 parts of xylene were charged, the polymerization was completed for 2 hours to complete the polymerization, and the solvent was removed under reduced pressure to obtain a resin (C1). GP of (C1)
The weight average molecular weight by C is 700,000, and the glass transition point is 60.
C., acid value was 0.26.

Production Example 2 763.9 parts of styrene and n-acrylic acid as mixed monomers
Butyl 234.4 parts, monobutyl maleate 1.5 parts,
A resin (C2) was obtained in the same manner as in Production Example 1 except that 0.2 part of divinylbenzene was used. The weight average molecular weight of (C2) by GPC was 700,000, the glass transition point was 61 ° C., and the acid value was 0.49.

Preparation of Resin (D) Production Example 3 452 parts of xylene was placed in the same apparatus as in Production Example 1, and after substitution with nitrogen, a mixed monomer of 845 parts of styrene and 155 parts of n-butyl acrylate at 170 ° C. and an initiator. As di-t-
A mixture of 6.4 parts of butyl peroxide and 125 parts of xylene was added dropwise over 3 hours. After dropping, the mixture was aged at 170 ° C. for 1 hour to complete the polymerization. Then, the solvent was removed under reduced pressure to obtain a resin (D1). The weight average molecular weight of (D1) by GPC is 13,000, and the glass transition point is 59 ° C.
Met.

Preparation of Resin B Production Example 4 764.3 parts of styrene, 234.9 parts of n-butyl acrylate, 0.8 parts of glycidyl methacrylate in an autoclave reaction vessel equipped with a thermometer, a stirrer and a nitrogen introducing tube. And a mixed monomer of 2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane as an initiator.
After adding 5 parts and polymerizing in a nitrogen stream at 90 ° C. for 5 hours, 245 parts of xylene were added, and polymerization was carried out at 90 ° C. for 1 hour and then at 110 ° C. for 1 hour. Furthermore, 2,2-bis (4,4-di-t-butylperoxycyclohexyl)
Add 0.2 parts of propane and 122 parts of xylene, and add 110 ° C.
After polymerizing for 4 hours at 150 ° C., 1 part of di-t-butyl peroxide and 25 parts of xylene were added and polymerized for 2 hours to complete the polymerization, and the solvent was removed under reduced pressure to obtain a resin (B1). . The weight average molecular weight of (B1) by GPC was 500,000, the glass transition point was 59 ° C., and the epoxy group in the total amount of 100 g of (B1) was 0.00053 mol.

Production Example 5 452 parts of xylene was placed in the same apparatus as in Production Example 1 and, after purging with nitrogen, 828.6 parts of styrene and n of acrylic acid at 170 ° C.
-Butyl 170.6 parts, glycidyl methacrylate 0.8
3 parts of a mixture of 6.4 parts of di-t-butyl peroxide as an initiator and 125 parts of xylene.
Dropped over time. After dropping, the mixture was aged at 170 ° C. for 1 hour to complete the polymerization. Then, the solvent was removed under reduced pressure to obtain a resin (B2). The weight average molecular weight of (B2) by GPC is 13,000, the glass transition point is 59 ° C., and
The epoxy group in 100 g of the total amount of 2) was 0.00056 mol.

Preparation of Resin (A) Production Examples 6 to 7 100 parts of xylene was charged into a cooling tube and a Kolben equipped with a stirrer, and the amount of (D) shown in Table 1 was added and dissolved.
(C) was added, the atmosphere was replaced with nitrogen, and the mixture was stirred at 150 ° C. for 2 hours.
It was stirred for a period of time to dissolve it uniformly. Then, the solvent was removed under reduced pressure at 170 ° C. to obtain resins (A1) to (A2). In Table 1 (A)
The Tg and the analysis value of the acid value are shown together.

[0029]

[Table 1]   −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−    Production Example Resin (C) (D) Tg ° C Acid Value   −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−       6 A1 C1 40 parts D1 60 parts 60 0.10       7 A2 C2 40 parts D1 60 parts 60 0.20   −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−

Examples 1 and 2 100 parts of xylene was charged into a cooling tube and a Kolben equipped with a stirrer, and the amount of (A) shown in Table 2 was used.
Was added and dissolved, and then (B) was added, and after nitrogen replacement, the mixture was stirred at 170 ° C. for 2 hours with stirring to uniformly dissolve. Then, the solvent was removed under reduced pressure at 170 ° C. to obtain (TB1) to (TB2). Table 2 also shows the weight average molecular weight of (B).

[0031]

[Table 2]   −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−    Example Resin (A) (B) BMW   −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−      1 TB1 A1 100 copies B1 12.6 copies 500000      2 TB2 A2 100 copies B1 12.6 copies 500000   −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−

Comparative Examples 1-2 The comparative toner binders (TB3 to TB4) were obtained in the same manner as in Example 1 except that the components shown in Table 3 were used. Table 3 also shows the weight average molecular weight of (B).

[0033]

[Table 3]   −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−    Comparative Example Resin (A) (B) BMW   −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−      1 TB3 A1 100 copies B2 12.6 copies 13000      2 TB4 A2 100 copies B2 12.6 copies 13000   −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−

Use Example and Comparative Use Example The toner binders were evaluated in two ways, a two-component developing system and a one-component developing system. Evaluation of Two-Component Development Method In each of 88 parts of the toner binders of the present invention of Examples 1-2 and the toner binders of Comparative Examples 1-2, 7 parts of carbon black (MA100 manufactured by Mitsubishi Kasei Co., Ltd.) and low molecular weight polypropylene (SANYO) Chemical Industry Co., Ltd. Viscole 5
50P) and 3 parts of a charge control agent (Hodogaya Chemical Co., Ltd., Spiron Black TRH) are uniformly mixed, and then kneaded by a twin-screw extruder having an internal temperature of 150 ° C., and the cooled material is finely pulverized by a jet mill. Then, the particles were classified by a dispersion separator to obtain toners a to d having an average particle diameter of 12 μm.

Test Example 1 97 parts of a ferrite carrier (F-100 manufactured by Powder Tech Co., Ltd.) was uniformly mixed with 3 parts of each of the toners a to d,
A commercially available copying machine (AR-5030 manufactured by Sharp Corp.) is used to transfer the toner image onto the paper, and the transferred toner is modified on the fixing unit of the commercial copying machine (BD-7720 manufactured by Toshiba Corp.). Then, a fixing test was performed at a speed of 35 sheets of A4 paper / minute. The image quality was judged by the image density after fixing. The test results are as shown in Table 4.

Test Example 2 Toners a to d were placed in polyethylene bottles,
After keeping it in a constant temperature water bath at 50 ° C for 8 hours, transfer it to a 42 mesh sieve and shake it for 10 seconds using a powder tester manufactured by Hosokawa Micron Co., Ltd., measure the weight% of the toner remaining on the sieve, and store it under heat resistance. It was a sex test.
The smaller the number, the better the heat resistant storage stability. If it is 35% or less, it is a level that can be used without problems. The results are shown in Table 4.

[0037]

[Table 4]   ---------------      Toner Toner MFT HOT Image quality Heat resistance             Binder (℃) (℃) Storability                       * 1 * 2 * 3 (%)   ---------------  Actual a TB1 130 ＞ 240 ○ 26  Application b TB2 131 240 ◎ 27  An example   ---------------  Ratio c TB3 140 220 ○ 26  Comparison d TB4 142 218 ◎ 27  An example   ---------------   * 1 The solid black portion with an image density of 1.2 was measured by the Gakushin type fastness tester (rubbing section = paper). Rubbing was repeated 5 times, and the image density of the solid portion after rubbing remained 70% or more. The heat roll temperature at which you got the copy.   * 2 Heat roll temperature when toner is hot offset   * 3 ◎: Image density (I.D)> 1.4, ○: (I.D) 1.0 to 1.4, △: (I.D) <1.0

In the evaluation by the two-component developing system, all of the toners a to b using the binder of the present invention have a heat-resistant storage stability as compared with the toners c to d using the comparative binder.
Excellent balance between low-temperature fixability and hot offset resistance without impairing image quality.

Evaluation of One-Component Development System Magnetic powder (EPT-1000 manufactured by Toda Kogyo KK) 48 was added to 48.8 parts of each of the toner binders of the present invention of Examples 1-2 and the toner binders of Comparative Examples 1-2. .8 copies,
After uniformly mixing 2 parts of low molecular weight polypropylene (Haimer TP-32 manufactured by Sanyo Chemical Industry Co., Ltd.) and 0.4 parts of a charge control agent (T-77 manufactured by Hodogaya Chemical Co., Ltd.),
The mixture was kneaded with a twin-screw extruder having an internal temperature of 130 ° C., and the cooled product was finely pulverized with a jet mill and classified with a dispersion separator to obtain toners A to D having an average particle size of 8 μm.

Test Example 3 Toners A to D were transferred to a toner image on paper by using a commercially available laser beam printer (LBP-210 manufactured by Canon Inc.), and the transferred toner on the paper was referred to as Test Example 1 described above. A fixing test and evaluation of image quality were performed by the same method. The test results are shown in Table 5.

Test Example 4 Toners A to D were subjected to the heat-resistant storage stability test in the same manner as in Test Example 2. If it is 35% or less, it is a level that can be used without problems. The results are shown in Table 5.

[0042]

[Table 5]   ---------------      Toner Toner MFT HOT Image quality Heat resistance             Binder (℃) (℃) Storability                       * 1 * 2 * 3 (%)   ---------------  Actual A TB1 132 ＞ 240 ◎ 25  Application B TB2 133 240 ◎ 26  An example   ---------------  Ratio C TB3 144 220 ○ 23  Compare D TB4 138 235 ◎ 24  An example   ---------------   * 1 The solid black portion with an image density of 1.2 was measured by the Gakushin type fastness tester (rubbing section = paper). The image density of the solid portion after rubbing was 70% or more after rubbing two times. The heat roll temperature at which you got the copy.   * 2 Heat roll temperature when toner is hot offset   * 3 ◎: Image density (I.D)> 1.4, ○: (I.D) 1.0 to 1.4, △: (I.D) <1.0

In the evaluation by the one-component developing method, all of the toners A to B using the binder of the present invention have a heat-resistant storage stability as compared with the toners C to D using the comparative binder.
Excellent low temperature fixability and hot offset resistance balance without impairing image quality.

[0044]

As described above, the toner binder of the present invention maintains heat-resistant storage stability and low-temperature fixability by introducing a small amount of reactive functional groups and has a high molecular weight, and is excellent in imageability and hot offset resistance. Toner is obtained.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Koji Yamakawa 1-11-11, Hitotsubashi-honcho, Higashiyama-ku, Kyoto Sanyo Chemical Industry Co., Ltd. (56) Reference JP-A-9-244295 (JP, A) JP-A 6-11890 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03G 9/087

Claims (7)

(57) [Claims] 1. An electrophotographic toner binder comprising a styrene-acrylic resin (A) having a carboxyl group and a styrene resin or a styrene-acrylic resin (B) having a functional group (b) that reacts with a carboxyl group. In (A), the weight average molecular weight is 200,000 to 200.
The high molecular weight polymer (C) has a weight average molecular weight of 3,000.
Consisting of a low molecular weight substance (D) having a molecular weight of up to 50,000,
A toner binder for electrophotography, wherein the acid value of (C) is less than 1 and the weight average molecular weight of (B) is 30,000 to 1,000,000. 2. The toner binder for electrophotography according to claim 1, wherein (b) is an epoxy group. 3. A total amount of 100 g of (B) is 0.0000.
The electrophotographic toner binder according to claim 1 or 2, containing 0 to 1 mol of (b). 4. The toner binder for electrophotography according to claim 1, wherein (b) contains (b) in an amount of 0.0001 to 1 mol per 1 mol of the carboxyl group in (A). . 5. The electrophotographic toner binder according to claim 1, which contains 0.1 mol% or less of a divinyl monomer as a constituent unit in (A). 6. The toner binder for electrophotography according to claim 1, wherein the carboxyl group in (A) and at least a part of (b) in (B) are reacted. 7. The electrophotography according to claim 6, wherein the reaction between the carboxyl group in (A) and (b) in (B) is produced up to at least a reaction rate of 70% without using kneaders. Toner binder.